Enterotoxins are toxins produced by Staphylococcus aureus, among other bacteria, which have various biological activities such as emetic, pyrogenic and mitogenic activities, inducing symptoms of food poisoning or being causative of toxic shock syndrome (TSS).
Staphylococci are broadly distributed in the skin, nasal cavity, oral cavity, throat, urinary organs and intestinal canal of various animals inclusive of man as well as in the air, sewage water, river, foods and so forth and encompass a broad spectrum of species. Among such numerous species of staphylococci, the one pathogenic to human beings is Staphylococcus aureus (hereinafter referred to briefly as S. aureus) which is a coagulase-positive bacterium. S. aureus induces various infectious diseases and can be a causative factor in nosocomial infections, thus being of social concern.
As the enterotoxin produced by S. aureus, the following 10 species are known to this day: staphylococcal enterotoxins A, B, C1, C2, C3, D, E, G, H and I (hereinafter referredtobriefly as SEA, SEB, SEC1, SEC2, SEC3, SED, SEE, SEG, SEH and SEI, respectively).
Enterotoxins are known to have superantigen activity. The ordinary antigen is taken up by the antigen-presenting cell and the antigen fragments available on fragmentation (conversion to peptides of 10 to 15 amino acids) are presented, in the form bound to the pockets of MHC (major histocompatibility complex) class II molecule, on the surface of the antigen-presenting cell. These fragments are recognized by the TCR (T cell receptor) α- and β-chains of certain T cell clones, whereby the T cells are activated to set an immune reaction going. On the other hand, in the case of a superantigen, the antigen is not fragmented but directlybound to the MHC class II molecule on an antigen-presenting cell, and then the complex is recognized by TCR on the T cell to thereby activate the T cell. In this process, the antigen is recognized by the Vβ region of the TCR but unlike in the case of an ordinary antigen, the superantigen is recognized by substantially the entire population of T cells expressing the specific Vβ region to induce activation of the T cells and, hence, production of cytokines. Thus, in an individual exposed to a superantigen, an enormous population of T cells is activated as compared with the ordinary specific immune response to consequently release cytokines within a brief time, thus being suspected to induce abnormal reactions of the living body.
By using a specific antibody against an enterotoxin, an MHC class II protein or the like, the enterotoxin can be removed from a body fluid such as blood, plasma or serum, a culture supernatant, a foodstuff or a beverage but such antibodies are not only expensive but have the drawback that sterilization causes denaturation and serious decreases in adsorptive capacity.
Therefore, the advent has been awaited of an enterotoxin adsorbent which may be produced easily at low cost and will be highly effective.
Incidentally, Japanese Kokai Publication Hei-10-290833 discloses an adsorbent for TSST-1 (toxic shock syndrome toxin-1) comprising a compound having a log P (P denotes a partition coefficient in an octanol-water system) value of not less than 2.50 as immobilized but the literature is reticent about adsorption of an enterotoxin.